The invention concerns a pump for generating at least two volume streams, in particular, a lubrication pump for internal combustion engines, drive pump and a pump for comparable applications.
Numerous lubrication pumps are known from the state of the art. These pumps deliver a relatively low maximum pressure level with a maximum of 7 to 8 bar. It has been demonstrated in many areas of application in the automobile industry—for camshaft adjusters, motor lubrication, and transmissions, for example—that pumps are required, which are cost-efficient and optimally constructed.
For example, camshaft adjusters are controlled by a lubrication pump, which, due to the limited pressure level in limited conditions, cannot ensure the function of the camshaft adjuster, because the pressure level of the lubrication pump is too low. A known solution is to employ a second pump as a high pressure pump for the maintenance of the camshaft adjuster. The higher pressure leads to a faster adjustment times by the adjuster.
It is common knowledge about transmissions that large volume pumps are employed with a volume stream of approximately 12 to 20 cm3/cycle, that circulate this volume stream at approximately 10 to 70 bar, even though only a small portion of the volume stream with these high pressures is required for changing gears and activating the clutch. Due to this, there are large losses of efficiency because of the pumps.
For motor lubrication, cost-efficient tandem pumps are employed, which are constructed with two sets of gears and two pump housing halves, whereby one pump-half is shutdown via a bypass to adjust these pumps at a certain pressure and volume stream level whereby a corresponding loss of efficiency occurs. As a basic principle, geared rotor sets are known from DE-A-196 46 359 and DE-Z-199 22 792. These are composed of an external ring having internal toothing and an eccentrically situated, externally-toothed gear located within the external ring, whereby the internal toothing is composed of rotatable rollers in the external ring, and has one more tooth than the external toothing, whereby an essentially smaller, fine-toothed module is superimposed on the external toothing of the gear, and each roller has a fine-toothing of the same module around its circumference, into which the teeth of the gear engage.
The function of the geared rotor set results in the following: a driving torque acts on the inner rotor via a drive shaft, turning the inner rotor. By this means, power is transferred from the toothed inner rotor to the epicyclic, or planetary gear. This produces percussive energy through the center of the planetary gear, on the one hand, and also a tangential force that produces torque on the planetary gear, whereby the percussive energy, which affects the bearing ring, sets the bearing ring into rotation.
The geared rotor set described above is suited to produce high pressures.